1. Field of the Invention
The present invention relates to heating coil assemblies, and in particular to a heating coil assembly suitable for use in a heavy duty hot air blower.
2. Description of the Prior Art
Heating coil assemblies are known in the art for use in various types of hot air blowing devices, such as paint-removing blowers, hair dryers and the like. Conventional heating coil assemblies are generally positioned adjacent to a blower fan and have a resistance heating element, generally in the form of a coil wire, disposed such that the blower moves air to be heated axially over the coil, such that when the air exits the assembly it has been elevated in temperature by the coil.
Many conventional units simply have the coil, and supporting means therefor, disposed openly within the housing of the blower device, such that the air passage surrounding the coil is a relatively large volume defined by the coil itself and the interior wall of the housing. Examples of such conventional devices are described in U.S. Pat. Nos. 3,943,329; 3,947,659; 3,109,083; 2,778,919; 2,730,609; 2,041,687; 1,955,240; 1,821,525 and 1,777,744.
Other known heating coil assemblies have a sleeve or other interior means surrounding the coil in the inside of the device housing, so as to define a smaller volume for passage of air over the coils. Examples of devices of this type are described in U.S. Pat. Nos. 4,198,556; 3,857,016; 3,668,370; 3,612,824 and 3,094,606.
A problem existing in the field of heating coil assembly manufacture is that of providing a reliable heating means which can be utilized for purposes requiring a sufficient volume of extremely hot air, such as for removing paint from a surface by causing the paint to blister by the application of intense heat thereto, is that of providing a heating element which meets these demands which is inexpensive, easy to assemble, and has relatively few elements. A further problem in the design and manufacture of such heavy duty heating elements is to provide such an element which generates sufficient heat for elevating the temperature of a large volume of air but which is sufficiently insulated from the remainder of the device so as to not cause a danger to the user.